Q. When the women arrived at Jesus’ tomb, was the tomb opened or closed?
A. Opened.

The passages cited as contradictory are the following:

“Now after the Sabbath, as it began to dawn toward the first day of the week, Mary Magdalene and the other Mary came to look at the grave. And behold, a severe earthquake had occurred, for an angel of the Lord descended from heaven and came and rolled away the stone and sat upon it.” (NASB)
– Matthew 28:1-2

“But on the first day of the week, at early dawn, they came to the tomb bringing the spices which they had prepared. And they found the stone rolled away from the tomb, but when they entered, they did not find the body of the Lord Jesus.” (NASB)
– Luke 24:1-3

Any confusion aroused in a reader of these passages comes from elementary misunderstanding of narrative. Notice that the verse in Matthew says a severe earthquake had occurred (past perfect tense). The stone was rolled away, but not right in front of the women visiting the tomb. They arrived after the fact, which is why they were so bewildered.
The other two gospel accounts support this record:

“They were saying to one another, ‘Who will roll away the stone for us from the entrance of the tomb?’ Looking up, they saw that the stone had been rolled away, although it was extremely large.” (NASB)
– Mark 16:3-4
“Now on the first day of the week, Mary Magdalene came early to the tomb, while it was still dark, and saw the stone already taken away from the tomb.” (NASB)
– John 20:1

You might wonder why Matthew 28:2 doesn’t appear to exercise past perfect tense in the King James Version. This is because our narrative culture has declined. We are not as accustomed to understanding the obvious inference in narrative as we should be. Many in the modern culture must have things spelled out for them. The New American Standard version has helped to better communicate the Bible as recorded in its original languages to contemporary English speakers.

On this website, I quote the Bible in NASB and have the RefTagger system set in KJV to familiarize readers with Tyndale’s superior language and help expand the mind.